The present invention relates to methods for producing sensors that include flexible substrates and one or more sensor electrodes, and in particular embodiments to sensor sets including such sensors.
Methods for producing sensors, particularly sensors useful in sensor sets for the determination of a body characteristic such as blood glucose levels, are known. Examples of such sensors, sensor sets and methods for production thereof are described, e.g., in commonly assigned U.S. Pat. No. 5,390,691; U.S. Pat. No. 5,391,250; U.S. Pat. No. 5,482,473; U.S. Pat. No. 5,299,571; U.S. Pat. No. 5,586,553; and U.S. Pat. No. 5,568,806, each of which is incorporated in its entirety herein by reference.
Certain known methods, such as that described in U.S. Pat. No. 5,391,250, form the sensor electrodes by an etching process. Etching processes are often multi-step procedures that can be time-consuming and expensive. Accordingly, a need exists for a simplified process for producing sensors.
Alternative methods described in PCT/US99/03781, published Sep. 10, 1999 and based on U.S patent application Ser. No. 09/034,422, form sensor electrodes by, for example, first forming a channel in a substrate, which can be a continuous web, and then depositing conductive material in the channel to form the electrode.
A need also exists for an improved process that enables continuous formation of sensors.
In accordance with one aspect of the present invention, there is provided a method of making a sensor that includes the steps of providing a pre-formed self-supporting flexible substrate; sputter-depositing a metal layer on the substrate; etching the sputter-deposited metal layers to form a sensor electrode having a proximal segment and a distal segment; plating a metal layer on the sensor electrode; and separating the sensor electrode and at least a portion of the substrate underlying the sensor electrode from the remainder of the substrate. Preferably, the substrate is comprised of a polymeric material, such as a polyimide, and in more particular embodiments, the substrate is supplied in the form of a continuous web.
In particular embodiments, a plurality of metal layers are sequentially sputter-deposited, and the plated layer is formed on the uppermost sputter-deposited layer of the sensor electrode. Preferably, the sputter-deposited metal layers are comprised of different metals, such as layers of chromium and copper.
According to particular embodiments, a plurality of sprocket holes are formed in the substrate adjacent to the sensor electrode. Also, in preferred embodiments, the step of removing the sensor is carried out using a laser.
In other embodiments, prior to the separation step, the sensor electrode is provided with a coating, such as a coating of a polymeric material, and/or a biocompatible polymeric material. Preferably, the coating is subsequently removed from the proximal segment and the distal segment of the sensor electrode. In further embodiments, the coating is removed from the distal segment of the sensor electrode and the distal segment is subsequently provided with an electrode chemistry. In other embodiments, the sensor electrode is provided with a membrane after the distal segment is provided with the electrode chemistry.
According to a particular embodiments, a plurality of sprocket holes are formed in the substrate adjacent to the sensor electrode. Also, in preferred embodiments, the step of removing the sensor is carried out using a laser.
In preferred embodiments, the substrate has an upper surface and a lower surface. The sensor electrode is formed on the upper surface, and after the etching step a bead is formed on at least one of the lower surface and the sensor electrode. The bead is formed, according to one particular embodiment, below and in alignment with the sensor electrode. According to another particular embodiment, a first bead is formed on the lower surface of the substrate and a second bead is formed on the sensor electrode. Preferably, the bead is formed using a liquid polymer, and is formed using a molding process.
In accordance with another embodiment of the present invention, a method of making a sensor includes the steps of providing a pre-formed self-supporting flexible substrate; sequentially sputter-depositing a plurality of metal layers on the substrate, the plurality of layers including an uppermost layer; plating a metal layer on the uppermost sputter-deposited metal layer; etching the plated and sputter-deposited metal layers to form a sensor electrode having a proximal segment and a distal segment; sequentially plating first and second metal layers on the sensor electrode; coating the sensor electrode with a polymeric material; forming at least one opening in the coating; and separating the sensor electrode and at least a portion of the substrate underlying the sensor electrode from the remainder of the substrate.
In preferred embodiments, layers of chromium and copper are sequentially sputter-deposited. Preferably, at least one layer of copper is plated on the sputtered layer(s) prior to etching, and layers of copper and gold are sequentially plated after the etching step.
In accordance with an additional embodiment of the present invention, a method of making a sensor includes the steps of providing a pre-formed self-supporting flexible substrate; sputter-depositing at least one metal layer on the substrate; etching the at least one metal layer to form a sensor electrode having a proximal segment and a distal segment; and separating the sensor electrode and at least a portion of the substrate underlying the sensor electrode from the remainder of the substrate.
In accordance with still another embodiment of the present invention, a method of making a sensor includes the steps of providing a substrate having an upper surface and a lower surface; sputter-depositing at least one metal layer on at least one surface of the substrate; etching the at least one metal layer to form a sensor electrode having first and second edges, a proximal segment and a distal segment; forming a bead on at least one of the upper surface and the lower surface of the substrate; and separating the sensor electrode and the portion of the substrate underlying the sensor electrode from the remainder of the substrate.
In preferred embodiments, the sensor electrode is formed on one of the upper and lower surfaces of the substrate and the bead is formed on the other surface of the substrate. In a further embodiments, the bead is formed on the substrate beneath the sensor electrode.
According to particular embodiments, the bead is formed by forming a perforation in the substrate adjacent to the first and second edges of the sensor electrode; securing the lower surface of the substrate to a mold, the mold having a channel that extends beneath the sensor electrode; flowing a liquid polymer over the upper surface of the substrate and through the perforations into the channel until the polymer beads on the upper surface of the substrate and covers at least a portion of the sensor electrode; curing the liquid polymer; and removing the substrate from the mold. In further embodiments, the perforations on each side of the sensor electrode include at least one perforation gap. The liquid polymer that flows over the sensor electrode does not cover the portion of the sensor electrode between the perforation gaps. The perforations on each side of the sensor electrode may include a plurality of perforation gaps. In still other embodiments, each perforation has a perforation gap adjacent to at least one of the proximal and distal segments of the sensor electrode. In a preferred embodiment, the distal segment is provided with an electrode chemistry.
According to yet another embodiment of the present invention, a method of making a sensor includes the steps of: providing a substrate having an upper surface and a lower surface; forming at least one channel in at least one of the upper and lower surfaces of the substrate; disposing a conductive material in the at least one channel to form at least one electrode; and forming a bead on at least one of the upper and lower surfaces of the substrate to produce a sensor.
According to a further embodiment of the present invention, a method of making a sensor includes the steps of: providing a substrate having an upper surface and a lower surface; disposing a conductive material on at least one of the upper and lower surfaces of the substrate by non-impact printing to form at least one electrode; and forming a bead on at least one of the upper and lower surfaces of the substrate to produce a sensor.
According to yet a further embodiment of the present invention, a method of making a sensor includes the steps of: providing a substrate having an upper surface and a lower surface; providing a film or sheet comprising a conductive material; transferring the conductive material from the film or sheet to the substrate to form at least one electrode; and forming a bead on at least one of the upper and lower surfaces of the substrate to produce a sensor.
According to still a further embodiment of the present invention, a method of making a sensor includes the steps of: providing a substrate having an upper surface and a lower surface; depositing at least one layer of a metal on the upper surface of the flexible substrate; etching the at least one metal layer to form a sensor electrode having first and second edges, a proximal segment and a distal segment; forming a perforation in the substrate adjacent to the first and second edges of the sensor electrode; securing the lower surface of the substrate to a mold, the mold having a channel that extends below the metal layer; flowing a liquid polymer over the upper surface of the substrate and through the perforations into the channel until the polymer covers the upper surface of the substrate and at least a portion of the sensor electrode; curing the liquid polymer; removing the substrate from the mold; and removing the sensor electrode, the cured polymer and the portion of the substrate between the first and second perforations by separating the substrate adjacent to the perforations.
According to another embodiment of the present invention, a method of making a sensor includes the steps of: providing a substrate; forming a bead on a surface of the substrate; forming a sensor electrode on the substrate; and separating the bead, the sensor electrode and at least a portion of the substrate between the bead and the sensor electrode from the remainder of the substrate.
According to yet another embodiment of the present invention, a method of making a sensor includes the steps of: providing a substrate; forming a sensor electrode on a surface of the substrate; forming a bead on the substrate; and separating the bead, the sensor electrode and at least a portion of the substrate between the bead and the sensor electrode from the remainder of the substrate.
In accordance with further embodiments of the present invention, sensors produced according to the foregoing methods are also provided. In accordance with other embodiments of the present invention, sensor sets that include sensors, as described herein, together with appropriate mounting bases and insertion needles are provided. In additional embodiments, the sensor sets include cannula in which portions of the sensor are disposed and which in turn are at least partially disposed within the insertion needles. In other embodiments, the sensor includes a bead, which is at least partially nested within the insertion needle, obviating the need for a cannula.
Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.